Dicty News Electronic Edition Volume 23, number 12 October 08, 2004 Please submit abstracts of your papers as soon as they have been accepted for publication by sending them to dicty@northwestern.edu or by using the form at http://dictybase.org/db/cgi-bin/dictyBase/abstract_submit. Back issues of Dicty-News, the Dicty Reference database and other useful information is available at dictyBase - http://dictybase.org. ============= Abstracts ============= Behavior of cellular slime molds in the soil J. T. Bonner D. S. Lamont Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey 08544 Mycologia, in press The cellular slime molds are soil organisms, yet ever since they were discovered in 1869 they have been studied on agar surfaces. Here the behavior of a number of species is examined and it is evident that they have different responses to directional light and they all thrive in the presence of soil. While phototaxis clearly plays a significant role in their ability to come to the soil surface for dispersal, even more important are gradients in the soil: both temperature gradients known from earlier studies, and as we show here, gas gradients-presumably ammonia as a repellent and oxygen as an attractant. There are numerous differences in both morphology and behavior among slime mold species, some of which are likely to be the result of natural selection to particular habitats, while others could more easily be explained by neutral phenotypic variation. Submitted by: John Bonner [jtbonner@Princeton.EDU] ----------------------------------------------------------------------------- Changes in spatial and temporal localization of Dictyostelium homologues of TRAP1 and GRP94 revealed by immuno-electron microscopy Hitomi Yamaguchi*, Tsuyoshi Morita**, Aiko Amagai, and Yasuo Maeda1 Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aoba, Sendai 980-8578, Japan Present address: *Department of Cell Genetics, National Institute of Genetics, Mishima, Shizuoka-ken 411-8540, Japan. **Department of Neuroscience (D13), Osaka University Graduate School of Medicine, Yamadaoka 2-2, Suita City, Osaka 565-0871, Japan. Exp. Cell Res., in press TRAP1 (tumor necrosis factor receptor-associated protein 1) is a member of the molecular chaperone HSP90 (90-kDa heat shock protein) family. In this study, we mainly examined the behavior of Dictyostelium TRAP1 homologue, Dd-TRAP1 during Dictyostelium development by immuno-electron microscopy. In vegetatively growing D. discoideum Ax-2 cells, Dd-TRAP1 locates in nucleolus and vesicles in addition to the cell cortex including cell membrane. Many of Dd-TRAP1 molecules moved to the mitochondrial matrix in response to differentiation, though Dd-TRAP1 on the cell membrane seems to be retained. Some Dd-TRAP1 was also found to be secreted to locate outside the cell membrane in Ax-2 cells starved for 6 h. At the multicellular slug stage, Dd-TRAP1 was primarily located in mitochondria and cell membrane in both prestalk and prespore cells. More importantly, in differentiating prespore cells a significant number of Dd-TRAP1 locates in the PSV (prespore-specific vacuole) that is a sole cell type specific organelle and essential for spore wall formation, whereas some Dd-TRAP1 in the cell cortical region of prestalk cells. These findings strongly suggest importance of Dd-TRAP1 regulated temporally and spatially during Dictyostelium development. Incidentally, we also have certificated that the glucose-regulated protein 94 (Dd-GRP94) is predominantly located in Golgi vesicles and cisternae, followed by its colocalization with Dd-TRAP1 in the PSV. Submitted by: Yasuo Maeda [ymaeda@mail.tains.tohoku.ac.jp>] ----------------------------------------------------------------------------- A brilliant monomeric red fluorescent protein to visualize cytoskeleton dynamics in Dictyostelium Markus Fischer 1, Ilka Haase 1, Evelyn Simmeth 2, Guenther Gerisch 2, and Annette Mueller-Taubenberger 2 1 Lehrstuhl fuer Organische Chemie und Biochemie Technische Universitaet Muenchen Lichtenbergstr. 4, D-85747 Garching, Germany 2 Max-Planck-Institut fuer Biochemie Am Klopferspitz 18, D-82152 Martinsried, Germany FEBS Letters, in press Red fluorescent proteins (RFPs) combined with GFP are attractive probes for double-fluorescence labeling of proteins in live cells. However, the application of these proteins is restrained by stable oligomer formation and by their weak fluorescence in vivo. Previous attempts to eliminate these problems by mutagenesis of RFP from Discosoma (DsRed) resulted in the monomeric mRFP1, and in the tetrameric RedStar RFP, which is distinguished by its enhanced fluorescence in vivo. Based on these mutations we have generated an enhanced monomeric RFP, mRFPmars, and report its spectral properties. Together with green fluorescent labels, we used mRFPmars to visualize filamentous actin structures and microtubules in Dictyostelium cells. This enhanced RFP proved to be suitable to monitor the dynamics of cytoskeletal proteins in cell motility, mitosis, and endocytosis using dual-wavelength fluorescence microscopy. Submitted by: Annette Mueller-Taubenberger [amueller@biochem.mpg.de] ============================================================================== [End Dicty News, volume 23, number 12]